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Cold air return

01-09-2010, 02:44 AM

I have a forced air furnace. The main cold air return that is directly above the furnace was reduced in size; does this reduction in size effect the efficiency of the furnace? Would it help to have any cold air returns on the top floor? The house is a framed two story with a basement.

Comment

If you can add some to each room upstairs it will greatly help comfort and keep it more even up and down. You would have to reduce the main floor one more or else path of least resistance will make additional registers useless.
Another benifit of adding more is that the noise will be spread out. I'm sure the central return you have now is very loud. Having it within line of sight to the blower makes that worse.
Sizing those will be tough. Hire a tech who knows air duct sizing, it'll be worth it.

Comment

I have multiple return airs in my house and I hardly hear the blower running at all. I was wondering since I have seen cold air returns in the floor and on the ceiling. What is the optimum location for these, and will it affect the efficiency of the furnace and air conditioning? I am completely remolding a rental property and have gotten a couple of different quotes one saying put them up high and the other saying to put them in the floor. Any suggestions?

Comment

Having a dual high and low return is optimal. The lower one would be closable. In the winter you want it open. It will take almost all the air off the floor (cold air falls and furnace heats it up) In the summer, close it, and will pull all the air from up high (heat rises and the AC will remove the heat)
So, both is best......or if you have more heating than cooling, low is the answer. If you have more AC, high is the answer.